SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12bb69a2a33f852a86fe04a8ece3263de718a42e5d1a583b06f39d4699779613' 
  AND token = '2u0GqXKujow4AKJLvccReni83JrLsabvjl4VGLZ+E8s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}